CVE-2026-0999

EUVD-2026-6102
Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 fail to properly validate login method restrictions which allows an authenticated user to bypass SSO-only login requirements via userID-based authentication. Mattermost Advisory ID: MMSA-2025-00548
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
5.4 MEDIUM
NETWORK
LOW
LOW
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
MattermostCNA
5.4 MEDIUM
NETWORK
LOW
LOW
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 11%
Affected Products (NVD)
VendorProductVersion
mattermostmattermost_server
10.11.0 ≤
𝑥
< 10.11.10
mattermostmattermost_server
11.1.0 ≤
𝑥
< 11.1.3
mattermostmattermost_server
11.2.0 ≤
𝑥
< 11.2.2
𝑥
= Vulnerable software versions
Common Weakness Enumeration
References
https://mattermost.com/security-updates